Chromis

It depends on what you want. On my nano the overflow was higher than the return. On my current 1.2M they are the same height.
I would guess, the only problem would be is that your sump should have enough room to accommodate the extra water that will rush down the return when a power outage happens

Yes agreed thank you. It just seems like the flowpump is being slowed down so much because of the pressure from the tank pushing back. Instead of having the overflow take that return pressure leaving the flow pump able to push a higher flowrate. I hope that makes sense, I am very new in the hobby and don't know all the terms. Thanks